With the development of the electronic industry, the structural stability and transmission rate of existing input/output (I/O) electrical connector assemblies installed on circuit boards are increased gradually as well in order to meet the requirement of consumers. An existing electrical connector assembly includes a plug connector and a socket connector that fit with each other. The socket connector includes an insulating body, multiple conductive terminals received in the insulating body, and a metal shell wrapping the periphery of the insulating body. An insertion space is formed between the metal shell and the insulating body, and the multiple conductive terminals are located in the insertion space. The plug connector includes a plastic body, multiple mating terminals fixed in the plastic body, and a shielding shell sleeved on the plastic body. When the plug connector is inserted in the insertion space, the shielding shell is located inside the metal shell, and the mating terminals are correspondingly in electrical contact with the conductive terminals to form electrical connection. However, when in use by a user, the plug connector and the socket connector can easily encounter a problem of over-loose fit or over-tight fit. If the fit between the plug connector and the socket connector is over-loose, i.e., the clearance between the shielding shell and the metal shell is too big, the plug connector can easily shake at a high amplitude in the insertion space, and as a result, the fit between the plug connector and the socket connector is not steady, easily causing poor contact. If the fit between the plug connector and the socket connector is over-tight, i.e., interference can easily take place between the shielding shell and the metal shell, the plug connector cannot be easily pulled out, and moreover, in the process of insertion and pulling, the surface of the shielding shell can be easily worn; after frequent insertion and pulling, the wear of the shielding shell will become severer, even the plating of the surface of the shielding shell will be worn out, and as a result, the appearance and electrical performance of the shielding shell will be severely affected.
Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.